More than 20 former footballers have so far come forward with allegations of historical child sex abuse in football, with five police forces investigating.
The Football Association has announced an internal review, an NSPCC hotline has received more than 250 calls and individual clubs are conducting their own inquiries.
Ex-Crewe defender Andy Woodward waived his right to anonymity to reveal his ordeal and several other former professionals have done the same.
One of the players who spoke out, former Tottenham and Liverpool midfielder Paul Stewart, said the sport could face allegations on the scale of the Jimmy Savile scandal.
After his death, former DJ and television presenter Savile was found to be one of the UK's most prolific sexual predators.
Here's what has happened so far.
Who has spoken out?
16 November: Former Bury and Sheffield United player Andy Woodward, 43, tells the Guardian he was sexually abused by convicted paedophile and former football coach Barry Bennell while at Crewe Alexandra between the ages of 11 and 15.
22 November: Steve Walters, 44, also claims he was sexually abused by Bennell while at Crewe. Walters, who in 1988 became the club's youngest debutant, also made the allegations to the Guardian.
23 November: Former England and Tottenham footballer Paul Stewart, 52, tells the Mirror he was sexually abused as a youth player. Stewart, who began his professional career with Blackpool and also played for Manchester City and Liverpool, claims an unnamed coach - not Bennell - abused him daily for four years.
23 November: Ex-Manchester City striker David White, 49, alleges he was also sexually abused by Bennell in the late 1970s and early 1980s, while playing for Whitehill FC junior team in Manchester.
24 November: According to the Guardian, an anonymous ex-footballer has contacted police to say he was a victim of George Ormond - a former Newcastle United youth coach who was jailed in 2002 for offences against young footballers in the area. Police are investigating an allegation of "historical sexual offences in Newcastle".
25 November: Two other men speak on Friday's edition of the Victoria Derbyshire programme. Jason Dunford and Chris Unsworth say they were abused by Bennell as youth players.
27 November: Anthony Hughes told the Sunday Mirror that Bennell abused him on a sofa while he was at Crewe Alexandra's centre of excellence.
27 November: As the FA announced an internal review of what it knew, former trainee footballer Ian Ackley told BBC Radio 5 live's Sportsweek about his abuse by Bennell.
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All those named above have waived their right to lifelong anonymity to speak out to the media.
What did the ex-footballers say?
Andy Woodward: "It was his way of finding out which players were the weaker ones or the softer ones. It started within a few weeks. Initially it was sexually touching but it rapidly got worse and he raped me. I don't want to put a number on how many times it happened, but it was over a four-year period."
Steve Walters: "I just had to pretend it never happened and block it out. I knew it could never come out and I was absolutely petrified because I thought that if it did ever come out that would be it for my career - finished. All these years, I've had this secret inside me. It's been unbearable but, just from reading the article from Andy, it already feels like a massive burden off my shoulders. I have to do this, and I just hope it will help bring more people forward, too."
Paul Stewart: "One day, travelling in the car, he started to touch me. It frightened me to death, I did not know what to do. It progressed to sexually abusing me. He said he would kill my mother, my father, my two brothers if I breathed a word about it. The mental scars led me into other problems with drink and drugs. The level of abuse got worse and worse. I was always under threat, if I was not playing well, he would threaten me with violence as well as sexual abuse. He was a monster."
David White: "While I believe throughout my football career I have come to terms with what had happened, I now realise the effects of Bennell's actions were much more far-reaching than I knew then. I have come to terms with the fact Bennell's actions influenced almost every event and relationship in my life."
Ian Ackley: "Once it finished it was a case of pretending it did not happen. It was almost like a double life. I was trapped in that dream of wanting to make it as a footballer. It was habitual - every weekend, school holiday, football trips."
Anthony Hughes: "As adults we now understand what was going on was just so terribly wrong. I cannot praise [Andy Woodward] Woody enough for his bravery in speaking out."
Who is Barry Bennell?
Barry Bennell has been taken to hospital after police responded to a "fear for welfare incident" at an address in Stevenage on Friday.
A statement from Thames Valley Police said: "Police officers attended an address in Knebworth Park, Stevenage just before 11pm on Friday, November 25 in connection with a fear for welfare incident.
"A 62-year-old man was located and was taken to hospital in order to receive medical treatment, where he remains."
Woodward, Walters, White and Ackley all say they were abused by Bennell.
He was sentenced to nine years in prison in 1998 after admitting sexual offences against six boys.
- Bennell was a youth coach at Crewe Alexandra in the 1980s and 1990s and also had a close association with Stoke City and Manchester City.
- He has been jailed three times for child sex abuse - including once in America.
- He was jailed most recently in 2015 for two years - with a minimum term of 12 months - for a historical sexual offence committed against a 12-year-old boy on a football pitch in Macclesfield.
- Florida Police said he had an "insatiable appetite" for young boys.
- His crimes were, at one point, the subject of a Channel 4 Dispatches programme.
- He described himself as a "monster" while giving evidence in court in 2015.
- He remains permanently suspended from football.
What have the clubs said?
On Thursday, Manchester City released a statement saying: "The club is aware of allegations that Barry Bennell had an association with Manchester City Football Club in the 1980s. As a result the club is currently undertaking a thorough investigation of any past links he might have had with the organisation."
Newcastle said they had not received any complaint, but would "cooperate fully with the police and relevant authorities".
On Saturday, Crewe announced they would hold an independent internal review into the way it handled historical child sex abuse allegations about their former coach Bennell.
On Sunday, PFA chairman Gordon Taylor said there were at least "six or seven clubs" including Blackpool, Leeds and Stoke connected with "particular individuals"
Blackpool and Leeds released statements saying neither club had received any information.
Have there been any arrests?
No, but five police forces are investigating so far - Cheshire, Hampshire, Northumbria, the Metropolitan Police and Greater Manchester.
Across the sporting industry, Operation Hydrant, the national police hub coordinating historical sex abuse claims, has said it is investigating 17 sports people and allegations of abuse at 24 sporting venues.
The Premier League said it was concerned by the allegations and urged those with information to come forward.
What has been the reaction?
Sports Minister Tracey Crouch said the former players had shown "incredible bravery" to speak out.
Former England striker Gary Lineker posted on Twitter after Stewart's story was published: "Wish my former Spurs team-mate Paul Stewart all the very best. Extremely courageous in telling his appalling story. Really hope his speaking out helps him and others. Utterly sickening."
Former England rugby union player Brian Moore - who was abused as a child - tweeted: "Football isn't to blame for recent sex abuse revelations but it does now have a responsibility to find out the extent of what happened."
Former England midfielder Danny Murphy, who came through the ranks at Crewe when Bennell was at the club, described the coach as "charismatic", but a "bit of a tyrant".
Murphy added the football environment is "a perfect breeding ground for anybody who wants to do things to children".
Manchester United and England captain Wayne Rooney, an NSPCC ambassador, said: "It's awful that some of my colleagues have suffered this way whilst playing the sport that I and they love. It's important that people know that it's OK to speak out, there is help available and that they don't need to suffer in silence."
The head of equality and safeguarding at the Football Association (FA), Sue Ravenlaw, said the "courage and dignity" shown by the four former footballers was "immense".
The Professional Footballers' Association (PFA) said it hoped other people affected will "have the confidence" to come forward as a result of the players' "bravery".
"I am expecting there will be more," PFA chief Gordon Taylor told BBC Radio 5 live's Sportsweek, adding he did not believe it would just be confined to north east and north west clubs.
"I am mindful it could be throughout the country where children are there; church, schools and other areas we are well acquainted with over the past few years."
- Watch: Paul Stewart says there will be 'hundreds' of victims
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- Listen: '5% of boys report being sexually abused in sport'
What have Crewe said?
On Saturday, Crewe said they were determined a thorough investigation took place at the earliest opportunity.
In a statement the club said it "believes an independent review, to be conducted via the appointment of external legal counsel, is the correct way forward in the circumstances".
Last week, Crewe chairman John Bowler told BBC sports editor Dan Roan he was "infuriated and very disappointed" about Bennell's crimes.
Bowler, who was chairman at the time of Bennell's offences, was asked whether more could have been done. He replied: "When we've done our inquiries and looked at the detail of the various accusations, then I'll be in a position to answer that kind of question."
Crewe director of football Dario Gradi, who has been associated with the club for more than 30 years and was manager from 1983 to 2007, said he "knew nothing" about Bennell's abuse of young footballers until his arrest in the US in 1994.
Woodward said it was "scandalous" Crewe had taken so long to address the case and said no-one at the club has ever apologised to him.
What about football's authorities?
Senior FA officials met Woodward on Thursday to discuss the allegations in more detail.
And on Sunday it instructed independent leading counsel Kate Gallafent QC to oversee its internal review, saying it would look into "what information the FA was aware of at the relevant times, what clubs were aware of, and what action was or should have been taken".
The FA said it was working closely with police, adding it "must ensure we do not do anything to interfere with or jeopardise the criminal process".
FA chairman Greg Clarke told BBC Sport that the crisis was "certainly the biggest he can remember", and that he was "angry" that people had "sleep-walked" through initial revelations in the 1990s.
Ravenlaw, meanwhile, reiterated the FA's safeguards:
- Criminal record checks are required for those in regulated activity with children.
- More than 35,000 people go through the FA's safeguarding children awareness workshop, or tailored training every season.
- The FA requires every club or league with affiliated teams who are under 18, to have a named, trained designated safeguarding officer, who has been criminal record checked.
Conservative MP Damian Collins told BBC Radio 4's Today programme on Monday that The FA has been too slow in reacting to allegations of sexual abuse in football and must launch a "much wider" inquiry.
The culture, media and sport committee chairman told the BBC the FA review into claims ex-players were abused as children needed to establish if there was a cultural problem in the sport.
- The FA is also supporting a hotline set up by the NSPCC. It is available 24 hours a day on 0800 0232642
How widespread could abuse be?
Woodward told the BBC's Victoria Derbyshire programme he believed his experience was "the tip of the iceberg".
Stewart, meanwhile, said "hundreds" of children may have been sexually abused by figures within football.
Asked if he feared the allegations football is facing could be as big as the Savile scandal, he told the BBC: "Yes, I do, for sure. I would almost guarantee it as long as the victims are willing to come forward."
The NSPCC's John Cameron said it could be "reminiscent of Operation Yewtree", a police investigation set up in 2012 to examine allegations of sexual abuse by Savile, which subsequently dealt with cases involving other celebrities.
"This is going to have an enormous impact," he told BBC Radio 5 live. "There are more players out there that both the NSPCC and FA strongly suspect have been victims of sexual abuse.
"It is an absolute disgrace and misuse of authority, and hopefully a number of people will be brought to account."
PFA chief Gordon Taylor said: "Because of Andy Woodward's bravery, many other ex-players and apprentices are now contacting us - it is double figures now - and that is a timely warning for everybody in football about our duty of care to these youngsters."
Could abuse still be happening?
Former Chelsea and Scotland winger Pat Nevin says he "wouldn't be surprised" to discover young footballers are still being sexually abused.
Nevin told BBC Radio 5 live he is "surprised" but not "shocked" by the recent allegations because he believes youth football provides a "ripe" environment for paedophiles to operate.
Former FA chief executive Mark Palios, now executive chairman at Tranmere Rovers, said he thought football was in a "better position today than 20 or 30 years ago".
"You can never be complacent you have got rid of it in the game, you have to be constantly vigilant," he told BBC Radio 5 live.
"This is a timely reminder, all clubs should test what happens in practice, they all have regulations and what is required these regulations are honoured. It is a wake up call to clubs to check these things."
Dr Daniel Rhind, a lecturer in social psychology at Brunel University, told BBC Radio 5 live one in 20 children could still be at risk of being sexually abused in sport.
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